Coins are an indispensable part of modern society, are a necessary tool for humans to exchange materials, and have a large circulation in our daily life. As the coins are increasingly widely used, traffic, financial, and other institutions increasingly rely on applications that judge denominations and authenticity of the coins and count the coins. At present, there are mainly the following several manners of counting the coins and identifying authenticity. (1) An alternating magnetic field is applied to a coin, then an induced eddy current field thereof is measured to judge the material of the coin, so as to identify the authenticity thereof; such a method measures an axial magnetic field of the coin mainly by using an induction coil or a combination of an induction coil and a Hall sensor, this can only measure one kind of signals that identify features, while for different coins having similar resonance frequencies, amplitudes or phases, such a method evidently cannot judge the authenticity accurately. (2) Multiple magnetoresistive sensors are used to form a sensor unit array to detect magnetic field distribution around the coin, so as to judge the denomination of the coin and the authenticity thereof, for example, the patent application CN103617669A discloses a coin detection device, such a device can also detect signals in only one direction, for coins that have similar diameters and have similar responses in the same direction, accuracy of the judgment result of such a method is not high enough, and the measurement result includes a new signal generated by an applied pulse field, subsequent processing is required to remove the signal, the operation process is relatively complicated, and the resolution may be reduced. (3) The authenticity of the coin is detected by performing variable-frequency input on a transmitting coil and measuring output of a receiver in different frequency points, for example, U.S. Pat. No. 4,086,527 discloses a testing method, although the method can obtain information such as amplitude, phase, and resonance frequency of the output signal, a single-axis sensor is still employed, and it is very difficult to identify some coins that have similar features. In addition, the authenticity may also be tested with methods such as using a pulse field for excitation and then removing the pulse field, and performing phase shifting, but all the methods can only provide one kind of signals that identify features, which cannot identify the coins that have the similar features accurately. As the coin forging technology is becoming increasingly excellent, the existing coin detection device cannot meet high precision requirements for coin detection in the modern institutions such as transportation and financial.